Acid-treated Carbon Nanotubes Research Articles

Enhanced performance of flexible polymer electrolyte membrane fuel cells with functional interlayer of heat- and acid-treated carbon nanotube sheets

Enhanced performance of flexible polymer electrolyte membrane fuel cells with functional interlayer of heat- and acid-treated carbon nanotube sheets

Mechanical and Tribological Properties of Carbon Fiber Reinforced POM Composite Filled With Maleamidic Acid Treated Carbon Nanotube

ABSTRACTIn order to attain improved mechanical properties of the carbon fiber (CF) reinforced polyoxymethylene (POM) composite, maleamidic acid treated carbon nanotube (CNT) was deposited on carbon fiber. The mechanical properties of composites have been investigated. The tensile strength values of the treated CF/POM composites at all CNT mixing ratios are found to be higher than that of untreated one. The surface morphologies of the fractured surfaces of the composites were recorded using scanning electron microscopy (SEM) to gain information about the fiber–matrix interfacial adhesion in the composites. The friction coefficient of all the CF/POM/CNT composites decrease as the load increases from 10 to 20 N under the same sliding speed of 1000 r/min. XPS results showed that the formation of C–O, C=O, and O–C=O based species give rise to chemical bonds of the CF and the POM.

Synergistic engineering of structural and electronic regulation in necklace-like UiO-66/ACNT structure toward lithium-sulfur batteries with fast polysulfide redox

Although UiO-66-based metal-organic framework (MOF) composites have been widely applied in the entrapment and catalytic effect toward lithium polysulfides (LiPSs), the synergistic engineering of structural and electronic regulation strategy has not been carefully considered. Herein, we optimize the internal cluster structure, rational regulate the size of UiO-66, and design the necklace-like structure composed of UiO-66 nanoparticles and acid-treated carbon nanotube (UiO-66/ACNT) through simple hydrothermal reaction and thermal treatment strategy. According to experiments and density universal function theory calculations, the improved UiO-66/ACNT architecture effectively provides more polarity to capture polysulfides via exposing more active sites and effectively delivers electrocatalytic activity of polysulfide conversion. Furthermore, systematic electrocatalytic kinetics, in situ Raman spectroscopy and in-situ impedance analysis indicate the functional separator can inhibit the shuttling effect, and catalyze the conversion of lithium polysulfide. As a result, Li-S batteries with functional separators exhibit excellent electrochemical performance (low fading rate over 1000 cycles of 0.06 % per cycle at 1C, high areal capacity of 4.01 mAh cm−2 at 0.2C). This work offers insight into the rational design of UiO-66-based metal-organic frameworks (MOFs) through synergistic engineering for high-performance Li-S batteries.

Effect of Synchrotron X-ray Irradiation Time on the Particle Size and DFAFC Performance of Pd/CNT Catalysts.

Global energy sources are limited, and energy requirements are ever-increasing due to the demand for developments in human life and technology. The environmentally friendly direct formic acid fuel cell (DFAFC) is an attractive electronic device due to its clean energy. In a DFAFC, an anodic catalyst plays an important role concerning the oxidation pathway and activity. In the present study, palladium (Pd) was synthesized by synchrotron X-ray photoreduction using various irradiation times (0.5-4 min) to control the particle size. An acid-treated carbon nanotube (A-CNT) was used as the template for Pd deposition. The A-CNT and Pd/A-CNT were examined using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and transmission electron microscopy to reveal the microstructural characteristics. Electrochemical evaluation, electrocatalytic activity, and the DFAFC performance of so-obtained Pd/A-CNT catalysts were investigated. The experiment's results showed that the Pd/A-CNT-2 (i.e., synchrotron photoreduction for 2 min) underwent a direct formic acid oxidation pathway and possessed a high ECSA value of 62.59 m2/gPd and superior electrocatalytic activity of 417.7 mA/mgPd. In a single DFAFC examination, the anodic Pd/A-CNT-2 catalyst had a power density of 106.2 mW/mgPd and a relatively long lifetime of 2.91 h. Pd/A-CNT-2 anodic catalysts synthesized by surfactant-free synchrotron X-ray photoreduction with a rapid processing time (2 min) are potential candidates for DFAFC applications.

Preparation of Conductive Composite Resin Using Metallic and Semiconducting SWCNTs

Carbon nanotube(CNT), which was discovered by Ijima, has been used wisely in various fields of materials due to their high-quality properties such as superior electrical conductivity, chemical stability and so on. Carbon nanotubes could be divided into two kinds, single-walled carbon nanotubes(SWCNTs) and multi-walled carbon nanotubes(MWCNTs). This classification is depending on carbon nanotubes' internal structure. Additionally, with further research, single-walled carbon nanotubes could be separate into metallic SWCNTs and semiconducting SWCNTs. One of the separation methods is using agarose gel electrophoresis, which was discovered by Tanaka. Based on the above method, researcher Kataura developed column separation of SWCNTs by using agarose gel without electricity. Although carbon nanotubes have been well-known for their properties, they can not exhibit them under normal conditions due to the agglutination that caused by intermolecular interaction. Therefore, to make carbon nanotubes exhibit their useful properties, technology of dispersing agglutinate carbon nanotubes is required. There are two major methods widely used to disperse CNTs currently. The first one is chemical dispersion. Increase carboxylic acid into strong acid-treated CNTs and use ultrasonic irradiation. However, excessive acid can cause damage to structure of CNTs which will make CNTs lose their original properties. Besides chemical dispersion, physical dispersion is a simple method which use ultrasonic irradiation to loosen agglutinate CNTs directly. However, in this method, re-agglutination is tend to occur, and excessive ultrasonic irradiation will also cause damage to the structure of CNTs. We have succeeded in developing CNTs' conductive composite resin with the method of dispersing CNTs by aromatic compounds.However, these resins developed by us have some shortages, such as lacking in conductivity. Although this degree of conductivity seems to reach the standard of touch screen, liquid crystal display's standard has not been reached yet. In our research, to increase the conductivity of risen, we tried to choose different kinds of CNTs, and consider that the metallic SWCNT would exhibit better conductivity than the CNT which was not separated.To test and verify if composite resin developed by metallic SWCNT could exhibit significant conductivity, we did a comparative experiment among metallic SWCNT, semiconducting SWCNT, and SWCNT without separation. Using these three types of SWCNT to develop composite resin, and then compared their conductivity.The result of the experiment above was unexpected, which showed semiconducting SWCNT's composite resin has the highest conductivity while metallic SWCNT has the worst conductivity. The prediction of this experiment's result was metallic SWCNT will exhibit the most significant conductivity because metal's conductivity is better than semiconductor under the normal condition. Through the inspection，we had a presumption that the effect of electron hopping lead to the highest conductivity of semiconducting SWCNT. Effect of electron hopping can occur in the field of semiconductor, the mechanism is that the electrons might leave their electron orbit because of external energy such as heat. In our experiment, phenylethyl alcohol was used as dispersion medium to disperse SWCNTs. Adding it to agglutinated SWCNTs will cause gaps between SWCNTs' molecules, electrons could change their orbits because of these gaps. During this effect, the movement of electrons will inflect the conductivity of the material. As a result, it was possible that semiconducting SWCNT exhibit high conductivity because of the effect of electron hopping which cause the movement of electron.

Synergistic influence of carbon nanotube-graphene oxide hybrid and nanosized interfacial TiC on the mechanical performance of Cu matrix composites

Reinforcement architecture and interfacial structure are two key factors affecting the performance of composites. Herein we attempted to achieve a comprehensive improvement of mechanical properties of carbon nanomaterials (CNMs) reinforced Cu matrix composites by means of reinforcement structure construction and interface structure optimization. Graphene oxide (GO) and acid-treated carbon nanotubes (AT-CNTs) were self-assembled into a GO-CNT hybrid structure through an ultrasonic mixing method, and then used as reinforcement of Cu matrix composite through the powder metallurgy method. The strengthening efficiency of GO-CNT hybrid was significantly higher than that of individual CNTs or GO, which could be attributed to the stable interconnected architecture of GO-CNT hybrid formed through sp3 hybridized C–C bonds and the larger interfacial area between them and Cu matrix. In addition, aiming at the issue of poor interfacial adhesion between the GO-CNT hybrid and Cu matrix, TiC nanoparticles were introduced onto the surface of GO-CNT hybrid through a pressureless spark plasma sintering strategy. The TiC nanoparticles can improve the interfacial wettability and optimize the interfacial bonding state. TEM results confirmed a semi-coherent interfacial lattice matching relationship between TiC nanoparticles and Cu matrix, which was conducive to forming robust interfacial bonding. Through the construction of hybrid reinforcement and the introduction of nanosized interfacial TiC, the GO-CNT hybrid reinforced Cu matrix composite has obtained ultra-high strengthening efficiency, and exhibited satisfied combination of strength and ductility. This study can provide a referential strategy for the comprehensive performance optimization of CNMs reinforced metal matrix composites.

Synthesized partially unzipped carbon nanotubes and potential DNA/CNTs interactions

Carbon nanotubes (CNTs) are structurally considered to be graphene nano-ribbons (GNRs) that rolled up into seamless tubes. While CNTs nanotechnology is advancing, synthesis of GNRs from CNTs is sought after for precise and integrative graphene applications. Acid treatment of CNTs can generate longitudinal unzipping in an effective, large scale and economic approach. However, further understanding of CNTs-to-GNRs degradation, which mimics biodegradation molecular processes by oxidants, can also aid to assess toxicological impact of biodegraded CNTs. In this study, unzipping of multi-wall carbon nanotubes (MWCNTs) was established using a strong oxidizing agent. The influence of oxidation on the morphological, crystalline quality and dielectric properties was investigated. In particular, partial unzipping of CNTs was confirmed by transmission electron microscopy (TEM), and scanning electron microscopy (SEM) images. Broad band dielectric spectroscopy (BDS) was utilized to depict the influence of the applied frequency on the dielectric properties. GNRs exhibited a lag in the drop of capacitance and impedance to higher values of frequency with respect to the starting MWCNTs. Furthermore, DNA interactions with partially unzipped carbon nanotubes, were computationally assessed by employing molecular docking. The obtained potential DNA-CNT molecular conformations were illustrated and their biomolecular implications were discussed.

High platinum utilization for proton exchange membrane fuel cells via low-temperature substrate sputtering on acid-treated carbon nanotube sheet

Low-temperature substrate sputtering on an acid-treated carbon nanotube (ATCNT) sheet result in high platinum (Pt) utilization. A thin catalyst layer (CL, ∼300 nm) with a high density of Pt and vacancies was formed on the ATCNT sheet (Pt-deposited ATCNT). It replaced the commercial carbon-supported Pt and microporous layers of the proton exchange membrane fuel cells. The substrate temperature (Tsub: 20, 5, −10, −30, and −50 ℃) contributed to crack formation in the porous Pt thin film and restrained the growth of Pt grain (average grain size from 8.60 to 3.97 nm). Below −10 ℃, the crack and grain size changed significantly. The increased crack and smaller grain size enlarged the Pt surface area while forming vacancies; this was confirmed via physical and electrochemical characterizations. When compared to Pt-deposited ATCNT (Tsub = 20 ℃, 47.61 m2 g-1Pt), the electrochemical surface area of Pt-deposited ATCNT (Tsub = -50 ℃, 72.06 m2 g-1Pt) increased by 51.35%. We present a high Pt mass-specific peak power density (5.93 kW g-1Pt), focusing on a strategy to increase Pt utilization.

Carbon nanotubes and silver nanoparticles modification of PVDF membranes for improved seawater desalination in direct contact membrane distillation

Membrane distillation (MD) has emerged as a novel technology capable of recovering fresh water from brackish, saline, and wastewater. However, its industrial application is limited to various challenges including membrane properties. In this work, the polyvinylidene fluoride (PVDF) membranes were modified to improve their performance towards desalination of simulated seawater particularly, acid treated carbon nanotubes (f-CNTs) and cellulose nanocrystals-capped silver nanoparticles (CNC-AgNPs) were incorporated into the PVDF matrix prior to casting. Simulated seawater (33.59 g/L) was used as the feed during DCMD tests. The modified membrane displayed improved tensile strength, surface roughness, and hydrophobicity. Interestingly, minimal leaching of AgNPs (0.378 ± 0.0628 ppm) was recorded within 72 h. Although water flux (0.179 ± 0.0303 kg/m2/hr) remained relatively low, salt rejection (99.8%) improved upon incorporation of NPs. This provides a one-step solution towards better performance in MD for recovery of freshwater from high saline seawater.

Acid-treated carbon nanotubes/polypyrrole/fluorine-doped tin oxide electrodes with high sensitivity for saliva glucose sensing

To alleviate the discomfort caused by the blood sampling process, a noninvasive saliva glucose sensor is investigated in this study. Owing to the low glucose concentration in the body fluid, the fabricated sensor is requested to possess high sensitivity. Herein, a chemical polymerization method is used to deposit polypyrrole (PPy) on a fluorine-doped tin oxide (FTO) conductive glass substrate followed by modification with acid treated carbon nanotubes (acid-CNTs) via the drop-casting method in order to fabricate acid-CNTs/PPy/FTO electrodes. In addition, the sensing device uses glucose oxidase as an enzyme to catalyze the redox reaction and improve the electrode selectivity. The electron transfer resistance decreases with layer-by-layer CNTs modification, and the acid-treatment time of CNTs significantly affects the sensing performance. The acid-CNTs/PPy/FTO electrodes exhibit excellent sensing performance with a high sensitivity of 95.26 μA/mMcm2 and a broad linear range of 10–700 μM with a R2 of 0.9958. Moreover, the acid-CNTs/PPy/FTO electrodes show high selectivity to glucose along with excellent stability. Furthermore, the sensing capability of the acid-CNTs/PPy/FTO electrode is tested using artificial saliva, that further confirms high potential of acid-CNTs/PPy/FTO electrodes in the noninvasive diagnosis of diabetes.

Lubrication Mechanisms of a Nanocutting Fluid with Carbon Nanotubes and Sulfurized Isobutylene (CNTs@T321) Composites as Additives

Developing high-efficiency lubricant additives and high-performance green cutting fluids has universal significance for maximizing processing efficiency, lowering manufacturing cost, and more importantly reducing environmental concerns caused by the use of conventional mineral oil-based cutting fluids. In this study, a nanocomposite is synthesized by filling sulfurized isobutylene (T321) into acid-treated carbon nanotubes (CNTs) with a liquid-phase wet chemical method. The milling performance of a nanocutting fluid containing CNTs@T321 composites is assessed using a micro-lubrication technology in terms of cutting temperature, cutting force, tool wear, and surface roughness. The composite nanofluid performs better than an individual CNT nanofluid regarding milling performance, with 12%, 20%, and 15% reductions in the cutting force, machining temperature, and surface roughness, respectively. The addition of CNTs@T321 nanocomposites improves the thermal conductivity and wetting performance of the nanofluid, as well as produces a complex lubricating film by releasing T321 during machining. The synergistic effect improves the cutting state at the tool–chip interface, thereby resulting in improved machining performance.

Preparation and Characterization of Polymer Membranes Impregnated with Carbon Nanotubes for Olive Mill Wastewater.

In this study, polymer membrane(s) impregnated with carbon nanotubes (CNTs) were developed, characterized and evaluated for removing phenolic compounds from olive mill wastewater; thus, protecting the environment and public health. Polyethersulfone/functionalized, multi-walled carbon nanotube (PES/fCNTs) membranes were synthesized via the phase inversion method using PES and acid-treated CNTs. The prepared membranes were then characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and contact angle. Results obtained from this study indicate a more hydrophilic surface for the prepared PES/fCNTs membranes, with a higher pure water flux compared to the polyethersulfone (PES) membranes. In addition, the amount of fCNTs in the membranes was found to be the most significant factor affecting the morphology and water flux of the membranes. The PES/fCNTs membranes at 1 bar with 0 wt.% and 1 wt.% of CNTs showed water flux of 37.8 and 69.71 kg/h.m2, respectively. In addition, PES/fCNTs membranes with 0.5 wt.% fCNTs showed the highest total phenol content removal of 74%.

Synthesis and Characterization of TiO2-Water Nanofluids

Nanofluids made of TiO2 and multiwalled carbon nanotubes are the focus of our study. Using TiO2 and water as the basic fluids, nanofluids were created in 100 : 0, 75 : 25, and 50 : 50 proportions. Carbon nanotubes (CNTs) were disseminated into these base fluids of three types at 0.125, 0.25, and 0.5 percentages. Over the course of two months, the change of zeta potential is monitored to assess the stability of the dispersion. XRD analysis and SEM and TEM analysis are carried out for TiO2 nanofluids. Nanoparticles were analyzed using EDAX analysis to identify their composition. SEM examination was used to investigate the morphology for TiO2 nanoparticles. Particles of TiO2 produced in this manner seemed to have an average diameter of 27 nm. Nanofluids have a poor stability, which is the most important aspect of employing them, although most studies did not focus on this. When it comes to nanofluids, this study is unique in that it provides an in-depth look of surface modification approaches that have been employed by researchers to address these issues, as well as an evaluation of their stability over two months. Solubility is improved by acid treatment of CNTs, which results in functional groups on the surface of CNTs.

Mechanical Properties and Characterization of Epoxy Composites Containing Highly Entangled As-Received and Acid Treated Carbon Nanotubes.

Huntsman–Merrimack MIRALON® carbon nanotubes (CNTs) are a novel, highly entangled, commercially available, and scalable format of nanotubes. As-received and acid-treated CNTs were added to aerospace grade epoxy (CYCOM® 977-3), and the composites were characterized. The epoxy resin is expected to infiltrate the network of the CNTs and could improve mechanical properties. Epoxy composites were tested for flexural and viscoelastic properties and the as-received and acid treated CNTs were characterized using Field-Emission Scanning and Transmission Electron Microscopy, X-Ray Photoelectron Spectroscopy, and Thermogravimetric Analysis. Composites containing 0.4 wt% as-received CNTs showed an increase in flexural strength, from 136.9 MPa for neat epoxy to 147.5 MPa. In addition, the flexural modulus increased from 3.88 GPa for the neat epoxy to 4.24 GPa and 4.49 GPa for the 2.0 wt% and 3.0 wt% as-received CNT/epoxy composites, respectively. FE-SEM micrographs indicated good dispersion of the CNTs in the as-received CNT/epoxy composites and the 10 M nitric acid 6 h treatment at 120 °C CNT/epoxy composites. CNTs treated with 10 M nitric acid for 6 h at 120 °C added oxygen containing functional groups (C–O, C=O, and O=C–O) and removed iron catalyst present on the as-received CNTs, but the flexural properties were not improved compared to the as-received CNT/epoxy composites.

High oxygen reduction reaction activity and durability of Pt catalyst photo-deposited on SnO2-coated and uncoated multi-walled carbon nanotubes

• Acid-treated CNTs were coated with SnO 2 by chemical method. • Platinum was photo-deposited on CNTs and SnO 2 -CNT supports. • Surface morphology was investigated by SEM and HAADF-STEM. • Pt/CNT and Pt/SnO 2 -CNT showed high oxygen reduction activity in acid media. Platinum nanoparticles were photo-deposited on acid-treated multi-walled carbon nanotubes (CNTs) and SnO 2 -coated CNTs. The SnO 2 -CNT nanocomposite was synthesised by a chemical method. Scanning and scanning transmission electron microscopy results indicated that the CNTs surface is partially covered by the SnO 2 layer. The surface morphology of the Pt catalyst depends on the nature of the support material. For instance, porous Pt aggregates of various sizes are formed at specific nucleation sites on the CNT surface, while a selective deposition of Pt was observed on the metal oxide part of the SnO 2 -CNT. Cyclic voltammetry and CO stripping investigations in 0.1 M HClO 4 solution confirmed different surface electrochemistry of the Pt catalysts. It is revealed that photo-deposition induces the formation of Pt-Sn nanoalloys due to increased interaction at the oxide interfaces. Both Pt/CNT and Pt/SnO 2 -CNT catalysts showed remarkable activity towards the electroreduction of oxygen in acid media. Durability measurement showed that photo-deposited Pt nanoparticles are more resistant to degradation. The corrosion-resistant nature of the SnO 2 -CNT support further improves the catalysts stability. Pt/CNT and Pt/SnO 2 -CNT catalysts retained 86% and 88% of the initial surface area respectively, after 10,000 potential cycles between 0.6 and 1.2 V RHE .

Polyvinylidene Fluoride/Nanoclays (Cloisite 30B and Palygorskite) Mixed Matrix Membranes with Improved Performance and Antifouling Properties

In this study, it was attempted to prove the effectiveness of nanoclays as economical and nontoxic nanofillers through comparison with carbon nanotubes (CNTs). Two hydrophilic nanoclays, namely, Cloisite 30B and palygorskite (PGS), were used as nanofillers to improve the morphology and performance of polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes. A nonsolvent-induced phase separation (NIPS) method was used to prepare mixed matrix membranes (MMMs). The effects of the nanoclays on morphology, performance, and antifouling properties of the prepared MMMs were investigated. It was found that compared to PVDF membranes, the hydrophilicity, antifouling properties, and morphology of the fabricated MMMs are improved significantly. Compared to PVDF membranes, pure water flux (PWF) values of the MMMs containing the optimum contents of Cloisite 30B (0.5 wt %) and palygorskite (1 wt %) improved by 44.7 and 61.7%, respectively. Acid-treated CNTs were used as a reference additive, and the performance and antifouling properties of the prepared PVDF/nanoclay MMMs were compared with the prepared PVDF/acid-treated CNT MMMs. It was found that the PWF values of the MMM containing optimum contents of PGS and Cloisite 30B nanoclays are 86 and 77%, respectively, compared with that of the MMM containing acid-treated CNTs. The PVDF/Cloisite 30B MMM exhibited lower PWF than the PVDF/PGS MMM, which could be attributed to the plate-like structure of Cloisite 30B. Also, the flux recovery ratio (FRR) values of the mixed matrix membranes containing optimum contents of PGS and Cloisite 30B nanoclays were 95.65 and 92.06%, respectively, compared to that of the MMM containing acid-treated CNTs. Also, the BSA rejections of the prepared MMMs containing optimum contents of Cloisite 30B and palygorskite were comparable with that of the MMM containing acid-treated CNTs. Therefore, nanoclays can be suggested as economical and ecofriendly nanofillers for improving the PVDF membrane performance.

Laser powder bed fusion additive manufacturing, microstructure evolution, and mechanical performance of carbon nanotube-decorated titanium alloy powders

Novel TiC-reinforced titanium matrix composites (TMCs) were in situ synthesized by laser powder bed fusion (L-PBF) of unique carbon nanotube (CNT)-decorated Ti-6Al-4V powders. Acid-treated CNTs were coated on the surface of Ti-6Al-4V particles by electrostatic self-assembly without varying the powder sphericity, leading to improved printability, as proved by laser-absorption and single-track experiments. During L-PBF, the CNTs were completely transformed into monocrystalline TiC dispersed in the α’-Ti matrix via a dissolution/precipitation mechanism. As illustrated by high-resolution transmission electron microscopy, the in situ-synthesized TiC crystals were closely bonded to the matrix, exhibiting typical TiC [001]//Ti [00−1] and TiC (220)//Ti (−100) orientation relationships. Significantly, the morphology of TiC underwent an interesting evolution from nanorods to micro-spheres, and to dendrites with an increase in the CNT content, causing a gradual increase in hardness of TMCs. This study may provide insights into the design of high-performance TMCs with unique microstructures, excellent properties, and tailored architectures.

Achieving a 3D Thermally Conductive while Electrically Insulating Network in Polybenzoxazine with a Novel Hybrid Filler Composed of Boron Nitride and Carbon Nanotubes.

To solve the problem of excessive heat accumulation in the electronic packaging field, a novel series of hybrid filler (BN@CNT) with a hierarchical “line-plane” structure was assembled via a condensation reaction between functional boron nitride(f-BN) and acid treated carbon nanotubes (a-CNTs). The reactions with different mass ratios of BN and CNTs and the effect of the obtained hybrid filler on the composites’ thermal conductivity were studied. According to the results, BN@15CNT exhibited better effects on promoting thermal conductivity of polybenzoxazine(PBz) composites which were prepared via ball milling and hot compression. The thermally conductive coefficient value of PBz composites, which were loaded with 25 wt% of BN@15CNT hybrid fillers, reached 0.794 W· m−1· K−1. The coefficient value was improved to 0.865 W· m−1· K−1 with 15 wt% of BN@15CNT and 10 wt% of BN. Although CNTs were adopted, the PBz composites maintained insulation. Dielectric properties and thermal stability of the composites were also studied. In addition, different thermal conduction models were used to manifest the mechanism of BN@CNT hybrid fillers in enhancing thermal conductivity of PBz composites.

High-Performance Asymmetric Supercapacitors Based on the Ni1.5Co1.5S4@CNTs Nanocomposites

In this paper, the Ni[Formula: see text]Co[Formula: see text]S4@CNTs nanocomposites containing different carbon nanotubes (CNT) content were prepared by a one-step hydrothermal method. More hydroxyl and carboxyl groups were introduced on the surface of CNTs by acidizing treatment to increase the dispersion of CNTs. The acid-treated CNTs can more fully compound with Ni[Formula: see text]Co[Formula: see text]S4 nanoparticles to form heterostructure. When the CNTs content is 10[Formula: see text]wt.%, the Ni[Formula: see text]Co[Formula: see text]S4@CNTs-10 nanocomposite exhibits the highest specific capacity of 210[Formula: see text]mAh[Formula: see text]g[Formula: see text] in KOH aqueous electrolytes at current density of 1[Formula: see text]A[Formula: see text]g[Formula: see text]. The superior performances of the Ni[Formula: see text]Co[Formula: see text]S4@CNTs-10 nanocomposite are attributed to the effective synergic effects of the high specific capacity of Ni[Formula: see text]Co[Formula: see text]S4 and the excellent conductivity of CNTs. An asymmetric supercapacitor (ASC) was assembled based on Ni[Formula: see text]Co[Formula: see text]S4@CNTs-10 positive electrode and activated carbon (AC) negative electrode, which delivers a high energy density of 61.2[Formula: see text]Wh[Formula: see text]kg[Formula: see text] at a power density of 800[Formula: see text]W[Formula: see text]kg[Formula: see text], and maintains 34.8[Formula: see text]Wh[Formula: see text]kg[Formula: see text] at a power density of 16079[Formula: see text]W[Formula: see text]kg[Formula: see text]. Also, the ASC device shows an excellent cycling stability with 91.49% capacity retention and above 94% Columbic efficiency after 10 000 cycles at 10[Formula: see text]A[Formula: see text]g[Formula: see text]. This aqueous asymmetric Ni[Formula: see text]Co[Formula: see text]S4@CNTs//AC supercapacitor is promising for practical applications due to its advantages such as high energy density, power delivery and cycling stability.

Composite of TiO2 nanoparticles and carbon nanotubes loaded on poly(methyl methacrylate) nanofibers: Preparation and photocatalytic performance

Carbon nanotubes (CNTs) are widely used in the preparation of composite functional materials with improved performance due to their unique electrical, mechanical properties and one-dimensional nanostructure. In this paper, the composite of TiO2 nanoparticles and acid-treated carbon nanotubes distributed on poly(methyl methacrylate) (PMMA) nanofibers was fabricated by sequential treatments of electrospinning, hydrothermal synthesis and freeze-drying. The resulting ternary composite of TiO2/CNTs/PMMA, which is featured with a specific surface area of 83.2 m2/g, effectively photodegraded a series of dyes, such as methyl blue, Rhodamine B, Sulforhodamine B and methyl orange (MO). In particular, complete degradation of MO (10 mg/L, 100 mL) was accomplished with TiO2/CNTs/PMMA (20 mg) in 40 min under UV irradiation. Moreover, the high photocatalytic activity of the ternary composite, which is superior to that of TiO2/PMMA, did not deteriorate during consecutive photodegradation tests up to ten runs. The photocatalytic mechanism of TiO2/CNTs/PMMA has been explored. The desirable high photocatalytic activity, excellent stability and easy recyclability of the ternary composite is attributed to the introduction of CNTs and the electrospun PMMA nanofiber support.